Lift truck



May 30, 1961 D. TRAVAGLIO LIFT TRUCK 5 Sheets-Sheet 1 Filed March 18', 1960 -IOZ RESERVOIR :m 5 WWW w -m% m E .0 vmfln m A W a D Y B 3 g F May 30, 1961 D. TRAVAGLIO LIFT TRUCK 5 Sheets-Sheet 2 Filed March 18, 1960 w O. m0 v 3m mm m Q E km mm W 0 mm D Attorneys y 1961 D. TRAVAGLIO 2,986,225

LIFT TRUCK Filed March 18, 1960 5 Sheets-Sheet 3 m A Horneys May 30, 1961 D. TRAVAGLIO LIFT TRUCK 5 Sheets-Sheet 4 Filed March 18, 1960 INi ENTOR. Dalny Travaglio BY Attorneys United States Patent LIFT TRUCK Dalny Travaglio, Berkeley, Calif., assignor to Yuba Consolidated Industries, Inc., a corporation Filed- Mar. 18, 1960, Ser. No. 15,944

7 Claims. (Cl.'180'9.52)

The invention relates primarily to a lift truck adapted to be driven under a load having a limited amount of ground clearance for the purpose of lifting the load sufficiently above the ground for transport and then carry ing-the load to a destination. A structure of this type is especially adapted for use in handling prepackaged ladingaboard ship or on a wharf and the like.

It is an object of the invention to provide a lift truck which can engage underneath a load supported a small distance from the ground and lift the load for transport, carry the load and then lower the load into engagement with the ground without any' instability or undue tilting orunevenness.

Another object of the invention is to provide a lift truck which has the propulsion machinery arranged in the very small space available beneath a load separated from the grounda short distance, for example, six inches.

Another object of the invention is to provide a lift truck which is capable of operatingover relatively rough surfaces such asoverlapped deck plates on a ship or on inclines or in cramped quarter's.

Another object of the invention is to provide a lift truck which is self-propelled and can be steered to move a load in a straight line or in a curved path under the direction of an operator.

Another object of the invention is to provide a lift truck inwhich close control over the propulsion mechanism is provided so that the lading can be accelerated, carriedand braked with precision.

' Another object of the invention is to provide a lift truck of improved characteristics.

Other objects of the invention, together with the foregoing, are attained inthe embodiments of the lift truck described inthe accompanying description and shown in the accompanying drawings in which:

Figure 1 is a plan of a lift truck constructed in accordance-*with the invention;v Y

Figure 2 is aside elevation of the lift truck of Figure 1 shown in raised position andwith the lading indicated by adotted outline thereon, certain portions being broken away to reduce the size of the figure;

Figure 3 is a diagram showing certain hydraulic circuitry utilized in connection with the lift truck;

Figure 4 is a plan with certain sections broken awayto disclose an interior construction illustrating part of the rn'echanism forraising. and'lowering the lift truck frame with respect to the ground-"engaging members;

Figure 5 is a cross-section of a detail of the structure shown in Figure 4, the plane of section being indicated by the line 5-5 of 4arid showing themechanism in lowered position; I

. Figure 6 is a view similar to Figure Shut showing the structure in elevated'o'r raised position;

. Figure'7 is-a' plan of one'of the propulsion units; cerjtain portions being brokenaway to disclose the interior construction generally in horizontal cross-section;

Figure 8 is a fragmentary view' showing parts of the mechanism of'Figu're 7, the planes of cross-section being indicated by the lines 8-8 of Figure 7;

Figure 9 is a view comparable to Figure 8 but showing in side elevation a part of a modified form of propulsion unit; and

Figure 10 is a cross-section, the plane of which is indicated by the line 10-10 of Figure 9.

The lift truck pursuant to the invention has been successfully embodied in commercial form and in a manner especially designed for use on shipboard and the like for carrying a standardized container 6. The container has a generally planar bottom 7 or floor which is normally supported from the ground on a pair of beams 8, the arrangement usually being such that the distance from the bottom of the beam 8 to the underside of the floor 7 is of the order of four inches. The weight which can be included in the container 6 varies but may be very great.

To lift and transport the container 6, there is provided a lift truck having a truck frame 11 comprised of a num' ber of structural shapes to give a generally rectangular platform in plan and including longitudinal members 12 and 13 on one side which are duplicated by similar members 14 and 16 on the other side. Since the vehicle is substantially symmetrical about a longitudinal center line, a description of one side is intended generally to apply equally to the other. Also included in the frame are various cross-members such as 17, 18, 19 and the like, all for the purpose of providing a substantially rigid frame work of slightly less vertical height than the room available between the bottom of the floor 7 and the bottom of the beams 8. I

In order that the-truck frame may be moved about over a supporting surface, it is provided with a number of ground-engaging propulsion units generally designated Hand 22 on the left side and 21R and 22R on the right side. These propulsion units are substantially identical except for symmetryand serve to support the weight of the vehicle and its lading upon the ground. Each of the support units, such as the unit 21 especially illustrated in Figures 5 and 6, has its own framework 23 and is con'- nected to the truck frame 11 in a particular way. As particularly illustrated in Figures 4, 5 and 6, spanning the truck frame members 12 and 13 is a pivot pin 24 on which is journalled a-boss 25 included in asupport arm 26;

At its lower end, the support arm carries an-axle 21 which extends through the frame 23 of the propulsion unit 21 so that the propulsionunit not only can rock in a fore and aft direction about the center of the axle 27 but so that the support arm 26 can pivot'about the pin 24 and in so doing can raise and lower the frame 11 respect to the ground. The support arm 26 is of sumcient breadth and is anchored on the frame andtothe propulsion unit in such a way that the frame 11 must rise and fall evenly with respect to the propulsion unit without any substantial wracking or twisting.

Special means are provided for affording relative vertical movement between the propulsion units and the main frame. Disposed on the'support arm 26 is a link 28 connected by a pin 29 for limited swinging movement with respect to the support arm. The link 28 not only carries a transverse reinforcement 31 but also has a transverse bar 32 resting upon a leaf spring 33 contained within an enclosed portion of the support arm and rastened by a machine screw 34 to an anchor 36 in the stat port arm. The link 28 is formed to provide a cam iricline 37 having an abrupt termination in a transverse wall 38.

Mounted on the truck frame 11 in ap'osition facing the cam incline 37 is a cam block 39 having a curved-cam su'i-fa'ce41 thereon. Designed to. abut and engage both the carnincline 37 and the cam*sur'face4'1-on the cam Patented May 30, 1961 arm. The slots 44 and 46 are substantially parallel to the cam incline 37 but are slightly shorter than the cam incline so that when the rod 43is'at one end 'of the slots 44 and 46, the roller 42 is substantially in abutment with the end wall 38.

Also connected to the rod 43 is one end of an actuating link 47 which at its other end carries a pin 48 serving as a journal for a second roller 49 in abutment with the under surface of the adjacent deck 51 included in the truck frame 11.

Each one of the ground-engaging propulsion units is provided with a similar support mechanism and in accordance with the invention means are provided for simul" taneously actuating all of the support arms so that the deck 51 and the entire main truck frame 11 are evenly raised and lowered with respect to the propulsion units. For this reason, the propulsion units 21 and 22 on the left side of a vehicle are joined by an actuating rod 52, portions of which are connected by a turnbuckle 53 (Fig. 6) so that careful adjustments can be elfectuated, although once an adjustment is made it normally need not be altered.

The actuating rod 52 is in part supported by the depending cam blocks 39 of each of the units and terminates in a clevis 54 near the rearward portion ofthe structure. Quite similarly, the right-hand propulsion units 21R and 22R are interconnected by a duplicate actuating rod 56 (Fig. 4) also terminating in a clevis 57. In order that the clevises 54 and 57 can be simultaneously actuated, a pair of hell cranks 58 and 59 are mounted on the truck frame 11. The left bell crank 58 is connected to the frame by a pivot pin 61 and is also connected by a pivot 62 to a connecting rod 63. Another pivot pin 64 joins the connecting rod 63 to the clevis 54. Similarly, the-bell crank 59 is connected to the frame 11 by a pivot pin 66 and is connected by a pivot pin 67 to a connecting rod 68. A pivot pin 69 joins the connecting rod 68 to the clevis 57.

The left bell crank 58 has an extension arm 71 joined by a pivot pin 72 to an equalizer bar 73. A pin 74 connects the other end of the equalizer bar with an extension arm 76 on the right bell crank.59. Thus, both. of the bell cranks 58 and 59 must rotate in unison about their respective pivot pins 61 and 66 and mustuniforrnly translate the clevises 54 and 57 through the intermediary of the connecting rods 63 and 68. The uniform translation of the side rods 52 produces uniform motion of all ofthe links 47 and of the support arms 26 so that the main frame 11 is always uniformly lifted andlowered with respect to the ground-engaging units.

The movement of the rods 52 from their Figure position toward their Figure 6 position is a bodily translation toward the rear of the frame 11. This translation occurs with the roller 49 hearing against the underside of the deck 51 on the truck frame and with the roller 42 earnming against both the cam incline 37 and the cam block surface 41. The force on the cam incline 37 is such that the cam incline tends to rotate about the pin 29 and to flex the leaf spring 33 until the cam incline block is in abutment with the lower portion of the adjacent support arm.

As the link 47 is bodily moved rearwardly, the roller 42, after rotating the cam incline, then drives the cam surfaces farther and farther apart, acting as a wedge. This produces a very powerful initial lifting movement of the main truck frame. As the lifting continues, the rod 43 encounters the end of the slots 44 and 46 at about the time that the roller 42 abuts the wall 38. At that point, the movement rearwardly of the roller 42 is arrested. Subsequent rearward movement of the rod 52 continues to produce a translation of the roller 49 which still bears against the deck 51; but further'movement of 4 the link 47 is like a toggle arm in producing further pivotal movement of the support arm 26 around the pin 24.

The linkage movement is in effect a compound one giving a very powerful initial lifting action due to the contour of the cam surfaces 41 and 37 and after the load has been lifted initially and after the link 47 is in a more advantageous position, the leverage that continues the lifting movement of the main frame is that due to the toggle action between the link 47 and the supportarm 26. Preferably, the rearward end of the slots 44 and 46 is provided with a downward enlargement 77 to allow space for the action of the leaf spring 33. The link 28 can thus rotate about the pin 29 to a limited degree under shock and overload conditions. Upon reversal of the movement of the rods 52, the platform 51 or deck and the main truck frame 11 are lowered with respect to the propulsion units, the action being just the reverse of that previously described. When the rod 43 is located within the enlargements 77, the spring 33 is of assistance in permitting such motion. The rod 43, being long, holds the parts in proper relationship when the entire vehicle is raised from the deck or ground by a crane, or the like.

Pursuant to the invention, the bell cranks 58 and 59 are preferably moved by a hydraulic mechanism. Suspended between the arms of the bell cranks 58 and 59 and in effect floating therebetween is a hydraulic jack 81 including a cylinder 82 and a piston rod 83. One end of the jack is connected by a pivot pin 84 to the left bell crank 58 while the piston rod 83 is connected to the right bell crank by a pin 86. Flexible hoses 87 and 88 extend from the jack 81 to a valve 89 (Fig. 3) controlled by an electrical mechanism 91 available to the vehicle operator.

A hydraulic circuit for the jack 81 under the control of the valve 89 is provided from a reservoir 92 on the truck frame 11. A filler standpipe 93 projects upwardly from the reservoir. An inlet conduit 94 leads to a pump 96 from which discharge occurs through a conduit 97 to the valve 89. A shunt pipe 98 connects to a pressure relief valve 99 from which a return line 101 extends back to the standpipe 93 so that the maximum pressure on the system is established. The valve 89 also has a return line 102 connected to the reservoir 92.

Upon manipulation of the valve 89, the jack 81 is forcibly projected to spread the bell cranks 58 and 59 apart or is forcibly contracted to compel the bell cranks 58 and 59 to approach each other. This mechanism affords a lifting motion, a lowering motion and, when the valve 89 is in neutral position, affords a holding position so that the main frame 11 and the deck 51 can be forcibly moved to and held in any selected position between the lowermost position and the uppermost position.

The hydraulic pump 96 is conveniently driven by an internalcombustion engine 103 mounted at the rear of the deck 51 on the main frame 11, the engine being provided with the customary accessories. This same engine is conveniently utilized to provide propulsive power for the lift truck. To that end, the engine 103 is connected through any suitable intervening mechanism with an electrical alternator 104 likewise mounted on the deck 51 of the main frame. The alternator supplies'suitable elet trical energy under the operators control, the details of the electrical control mechanism forming no part of the present invention. However, the control instrumentalities are such that both of the propulsion units 21 and 22 are simultaneously controlled for forward, reverse or no motion whereas the right-hand propulsion units 21R and 22R are controlled as a unit both for forward and reverse motion and for no motion. "The control of the left-hand units is entirely separate and distinct from the control of the right-hand units. The mechanism is such that the left-hand units can be propelled forward or reverse while the right-hand units are propelled forward or assagasa reverse. This affords quick steering ofthe mechanism. and a sharp turn about the virtual center of the structure. If all of the units are propelled together forwardly or in the reverse direction, there is a straight line movement of the vehicle. The control is such that any steering movement or direction is easily effected.

Electrical energy from the alternator 104, after having passed through suitable control instrumentalities, is carried to the individual propulsion units, all of which have substantially identical driving mechanism except for symmetry and are as represented in Figures 7 and 8 which show the unit 21. Within the frame of this unit there is mounted an alternating current electric motor 1'11 joined by a flexible coupling 112 to a gear reducer 113, the housing of which is within and may form part of the housing of the propulsion unit. The speed of the motor 111 is thus reduced to drive a bevel pinion 114 at a slower rate. The pinion 114 is in mesh with a bevel ring gear 116 on a cross-shaft 117 mounted in the gear reducing unit. Also on the shaft 117 is a drive gear 118 meshing with an idler gear 119 in turn meshing with a driven gear 121. These latter gears are in an auxiliary gear housing having a separate cover 122 but form part of the propulsion drive unit.

The gear 121 is fast on a driven shaft 123 spanning the sides of the propulsion unit frame and between them carrying a toothed rotor 124. The rotor 124 has transversely extending teeth 126 on its periphery to engage with a timing belt 127 not only trained around the rotor 124 but extending for substantially the full length of the propulsion unit. The belt 127 is also trained around a similar toothed rotor 128 at the trailing end of the propulsion unit frame. The rotor 128 is on an adjustable shaft 129 positioned by adjusting screws 131 and 132.

Substantially tangent to the lower portion of the rotors 124 and 128 is a support plate 133 conveniently formed as part of the housing for the gearing and motor. The plate 133 extends forwardly substantially to the rotor 124 and extends rearwardly to a terminus -134 just ahead of the rear rotor 128. The timing belt 127 is propelled by rotation of the forward rotor 124 and slides over the weightbearing plate 133. The weight of the lading and of the truck frame is evenly distributed over the four timing belts on the four propulsion units.

As a modification of this arrangement and as illustrated in Figures 9 and 10, the forward rotor 140 comparable to the rotor 124 includes a plurality of side-byside sprockets 141 all on the shaft 123. The rearward rotor 142 includes a similar plurality of side-by-side sprockets 143 on the shaft 129. The plate 144 between the forward rotor 140 and the rearward rotor 142 preferably has longitudinal lands 145 extending downwardly therefrom to provide intervening grooves 146. Trained around the groups of sprockets 141 and 143 is a link belt 147 made up of side links 148 with anti-friction rollers 149 therebetween in the customary fashion all connected by chain pintles 151.

The operation of the link belt or chain belt structure is substantially the same as that of the timing belt. Rotation of the forward sprocket rotor 140 drives the chain belt 147 with the rollers 149 rolling on the lands 145 and with the intervening links 148 being accommodated in the grooves 146. The links serve to prevent lateral dislocation of the chain belt from the support plate 133 so that side thrust on the link belt due to steering of the vehicle does not dislodge the belt.

While both of the structures shown in Figures 7 and 8 particularly, or as disclosed in Figures 9 and 10, operate well in practice, it is for most purposes preferred that the structure of Figures 9 and be utilized since while it is not in some respects as smooth in operation as the Figures 7 and 8 structure, it is less susceptible to lateral displacement of the traction elements.

In the operation of this structure, the operator manipulates the hydraulic mechanism to raise and lower the truck frame and customarily leaves the frame in a somewhat depressed position and controls the operation of: the

internal combustion engine 103 to supply suflicient use. tn'city by means of'the alternator to the various alternating current motors 111 in the various propulsion units. The operator controls thespeed of the motors in the lefthand units and in the right-hand units in such a way as to steer or direct the vehicle to the place desired.

Approaching a container 6, the main truck frame is lowered entirely or sufficiently so that it can be driven by the continued operation of the propulsion units into a location beneath the lading and between the beams 8. As soon as the lading is against stops 152 near the rearmost portion of the main frame, the operator appropriatelyactuates the hydraulic jack 81 so that the bell cranks, the various connecting rods and the linkages are actuated to lift the truck frame up into abutting contact with the bottom 7 of the lading 6 and to lift the lading to a maximum height.

The electric motors 111 are then further energized and the vehicle with the lading is moved either forwardly or rearwardly and is steered to the left or right or is spun around to carry the elevated lading to the desired location. During vehicle travel, the individual propulsion units, being pivotally mounted on the axles 27, are free to oscillate without much disturbance of the remaining mechanism. The vehicle easily and smoothly encounters any gradients and overrides any irregularities in the ground or other supporting surface.

The lading is brought to the desired point for deposit and the propulsion motors are reversed as brakes or are stopped. The hydraulic jack 81 is actuated in the reverse direction by manipulation of the valve 89 under the electrical control 91 so that the truck frame is lowered. This not only lowers the deck 51 but also lowers the lading until it rests upon the ground again supported on the beams 8. The deck is lowered slightly farther and then the electric motors 111 are again energized in a reverse direction so that the entire lift truck mechanism is backed out from underneath the lading and is then available for future use elsewhere.

What is claimed is:

l. A lift truck comprising a truck frame, a plurality of ground-engaging propulsion units disposed beneath said frame, a plurality of support arms one for each of said propulsion units, means for pivoting one end of each of said arms to said truck frame, means for pivoting the other end of each of said arms to a respective one of said propulsion units, a cam incline on each of said arms, a plurality of cam blocks on said frame each being opposite a respective one of said inclines, a plurality of actuating links, means for disposing one end of each of said actuating links between respective ones of said cam blocks and inclines, and means for simultaneously moving the other ends of said links along said truck frame.

2. A lift truck comprising a truck frame, a groundengaging propulsion unit disposed beneath said frame, a support arm, means for pivoting one end of said support arm to said frame and the other end of said support arm to said propulsion unit, a cam incline on said arm, means forming a bearing surface on said frame, an actuating link, means at one end of said actuating link abutting said cam incline and said bearing surface, means at the other end of said actuating link abutting said truck frame, and means for moving said other end of said actuating link along said truck frame.

3. A lift truck comprising a truck frame, a ground-engaging propulsion unit disposed beneath said frame, a support arm, means for connecting one end of said support arm to said truck frame and the other end of said support arm to said propulsion unit, a cam incline on said support arm, means forming a slot in said support arm parallel to said cam incline and substantially coextensive with said incline, a cam block on said truck frame facing said cam incline, an actuating link, a rod passing through one end of said link and running in said slot, a first roller on said rod and abutting said cam incline and said cam block, a second roller mounted on the other end of said link and abutting said truck frame, and means for moving said second roller along said truck frame. 4. A lift truck comprising a truck frame, a groundengaging propulsion unit disposed beneath said frame, a support arm, means for connecting one end of said support arm to said truck frame and the other end of said support arm to said propulsion unit, a cam incline on said support arm, means forming a slot in said support arm parallel to said cam incline and substantially coextensive with said incline, a cam block on said truck frame facing said cam incline, an actuating link, a rod passing through one end of said link and running in said slot, a first roller on said rod and abutting said cam incline and said cam block, a second roller mounted on the other end of said link and abutting said truck frame, and means for moving said link bodily with said second roller moving along said truck frame and said first roller advancing along said cam incline and said cam block until said rod encounters the end of said slot and then continuing the movement of said second roller along said truck frame to pivot said support arm.

5. A lift truck comprising a truck frame, a plurality of ground-engaging propulsion units disposed beneath said frame, a plurality of individual support arms one for each of said propulsion units, means for separately pivoting one end of each of said arms to said truck frame, means for separately pivoting the other end of each of said arms to a respective one of said propulsion units, means interposed between said truck frame and each of said propulsion units for moving said propulsion units toward and away from said frame, means on said truck frame including a pair of bell cranks for separately actuating said moving means, and means including a hydraulic jack suspended solely by said bell cranks for operating said actuating means.

6. A lift truck as in claim 5 in which an equalizer bar is connected to said bell cranks.

7. A lift truck as in claim 2 in which said propulsion unit includes a pair of toothed rotors, a ground-engaging link belt encompassing said toothed rotors, an a grooved supporting plate having lands thereon in engagement With said link belt between the links thereof.

References Cited in the file of this patent UNITED STATES PATENTS 

